Epidemiology of Guillain-Barré Syndrome in Iranian Children Aged 0-15 Years (2008-2013)

Objective Guillain-Barré Syndrome (GBS) is an acute inflammatory polyneuropathy characterized by a rapid progressive symmetric weakness. The GBS is the most common cause of acute flaccid paralysis (AFP) in most parts of the world. This study was carried out to investigate the epidemiological features of GBS in Iranian children. Materials & Methods The data were extracted using the AFP surveillance system that is a national screening program to detect all cases of AFP aged 0-15 years around the country. National Population Statistics data and AFP demographic data during 2008-2013 intervals were obtained from the relevant authorities in the Ministry of Health in Iran. The GBS cases were then extracted from the aforementioned database. The Chi-square test and Fisher’s exact test were used for statistical analysis. Results A total of 1884 cases of GBS were identified in the study period, and the average annual incidence rate was 1.72 per 100,000 individuals. The highest incidence rate was within the range of 0-5 years. There was no statistically significant relationship between the incidence of GBS and the season in the whole country. Conclusion High costs of GBS treatment, morbidity and occasional mortality, and number of new cases, which is estimated to be approximately 300 individuals per year, need the particular attention of the health system.

The GBS is the most common cause of subacute and acute flaccid paralysis (AFP) in neonates and children. All age groups can be affected by GBS, and it seems that adults are more susceptible than children. The worldwide incidence of GBS for all ages has been estimated to be within the range of 0.4-2.4 per 100,000 individuals. The annual incidence in children seems to be lower estimated to be within the range of 0.4-1.3 per 100,000 individuals.
The prognosis of GBS in children is generally excellent that is quite different from adults who have higher morbidity and mortality (4). There is no significant difference in GBS incidence among seasons, although a limited number of studies suggested a seasonal variation (1). With this background in mind, the current study aimed to determine the annual incidence of GBS in children, analyze morbidity and mortality rates, and compare these rates according to age, gender, and geographical and seasonal variations.      this means that the major manifestation was a motor deficit. In addition, theoretically, this study could have missed rare cases of acute sensory neuropathy with only sensory nerves or roots involvement and atypical cases, such as Miller Fisher syndrome that is not presented with flaccid paralysis. However, this fact can have a negligible effect since these atypical cases are rare (less than 5%), and they can only change the incidence of GBS by approximately 0.1 per 100.000 individuals (8,9).

Materials & Methods
A recent study from Bangladesh showed an incidence rate of 1.5 to 2.5/100,000 individuals per year in children under 15 years of age (10), indicating a probable increase in childhood GBS incidence. With a mean incidence of 1.72 per 100,000 individuals, the present study supports the aforementioned hypothesis. This presumed rise in incidence could be explained by a better diagnosis of the disease by physicians, a better national registry network, and the emergence of many new environmental factors (i.e., chemical, physical, and microbiological) that can modulate the immune system. However, researchers should wait for performing extensive surveys from other countries to document the possible rise in GBS incidence.
In a 6-year cross-sectional study (2001)(2002)(2003)(2004)(2005)(2006) in East Azerbaijan, Iran, Barzegar (12). The male to female ratio was 1.27:1 in the present cohort that is almost similar to those of other countries in all age groups.
Childhood GBS generally has a good prognosis in contrast to adult GBS with higher morbidity and mortality (4 (1989 -1999) in Honduras, the mortality rate in childhood GBS was 7.3%. Most of the mortality cases of the present study occurred in children under 5 years of age. The reason for this age distribution is the non-specificity of symptoms in early childhood, delay in the correct diagnosis, and vulnerability of young children to respiratory failure and autonomic dysfunction (14).
Residual motor deficit after 60 days of paralysis onset annually ranged from 22.7% to 35.1%. In this study, there was no longer follow-up for the patients. Vajsar J et al. reported a persistently decreased muscle power (with at least one muscle group having movement against gravity but with minimal resistance against a force) in 23% of children with GBS during an average 5-year follow-up in Toronto (13).

No significant seasonal variation in GBS incidence
was reported in other studies (15)(16)(17)(18), although a Brazilian study showed outbreaks in spring and summer (19) and another study in Netherland showed an increase in incidence in winter and June (20). Xiujuan Wu et al. reported a higher incidence of childhood GBS in summer (21). Despite different climates in Iran, there was no significant difference in the seasonal incidence of GBS in the patients of this study.
The age distribution of GBS is bimodal according to some studies, with peaks occurring in young adults and the elderly (2,22,23). In the current study, 50% of all GBS cases were within the age range of 1-5 years, for which there was no explanation and no similar results were obtained in other studies.